Defense Secretary Lloyd J. Austin III presented himself before a congressional committee for chastisement on Thursday, continuing a round of mea culpas over his failure last month to tell his boss that he was in the hospital with complications from prostate cancer surgery.
Republican lawmakers had been preparing to lay into Mr. Austin before the hearing, calling former Defense Department officials for advice. Even the formal title of the hearing, listed on the House Armed Services Committee’s website, struck an ominous tone: “A Review of Defense Secretary Austin’s Unannounced Absence.”
Mr. Austin sought to get ahead of the expected scolding by apologizing — again — for keeping his hospitalization at Walter Reed National Military Medical Center a secret.
“We did have a breakdown in notifications during my January stay at Walter Reed — that is, sharing my location and why I was there,” he told the packed hearing room. “And back in December, I should have promptly informed the president, my team, and Congress and the American people of my cancer diagnosis and subsequent treatment.”
He added: “I take full responsibility.”
On Monday, the Pentagon released an unclassified version of a review of how Defense Department officials, including Mr. Austin, handled his hospitalization. The document offered little if any criticism and faulted no one for the failure to disclose his illness.
Even before the hearing began, lawmakers had been steaming. Representative Mike D. Rogers, Republican of Alabama and the chairman of the Armed Services Committee, resorted to capital letters to make his point on social media that “the review of Sec Austin’s actions, conducted by his own subordinates & subject to his approval, HELD NO ONE ACCOUNTABLE.”
In his opening statement on Thursday, Mr. Rogers said the chain of command “doesn’t work” when the president does not know whom to call.
“It’s totally unacceptable that it took three days to inform the president of the United States that the Secretary of Defense was in the hospital, and not in control of the Pentagon,” Mr. Rogers said as he opened the hearing. “Wars were raging in Ukraine and Israel, our ships were under fire in the Red Sea, and our bases were bracing for attack in Syria and Iraq. But the commander in chief did not know that his secretary of defense was out of action.”
Mr. Rogers added: “Someone needs to be held accountable.”
On the other side of the Capitol, senators from both parties voiced frustration after receiving a classified briefing on the Pentagon’s review on Tuesday.
“I have very strong, severe questions remaining for the Pentagon as to how this seeming concealment was handled, and I think there ought to be some public accountability,” Senator Richard Blumenthal, Democrat of Connecticut, told reporters.
Senator Roger Wicker of Mississippi, the senior Republican on the Armed Services Committee, said in a statement, “I remain concerned that the department has yet to account for its failure to comply with federal law and notify Congress or the White House that the secretary was incapacitated.”
Mr. Wicker added, “It is clear that many members of the committee left the briefing frustrated by questions that went unanswered.”
Mr. Austin underwent an elective medical procedure at Walter Reed on Dec. 22. He did not tell the White House or senior administration officials that he was having surgery for a diagnosis he would later describe as a “gut punch.”
He was released before Christmas but returned on New Year’s Day with complications that kept him in the intensive care unit for two weeks.
Mr. Austin’s chief of staff, Kelly Magsamen, did not inform the White House that her boss was in the hospital until three days later. The extraordinary breach of protocol — Mr. Austin is in charge of the country’s 1.4 million active-duty service members at a time when wars in Gaza and Ukraine dominate the American national security landscape — baffled officials across the government, including at the Pentagon.
Mr. Austin tried to explain himself in early February when he told reporters at the Pentagon that “I did not handle this right.”
“I should have told the president about my cancer diagnosis,” he said. “I should have also told my team and the American public, and I take full responsibility.”
Mr. Austin also said he never told his staff not to inform the White House about his hospitalization.
The defense secretary has long been known as extremely private and media shy.
